Oscar-winning actor Philip Seymour Hoffman was found dead Sunday in his Manhattan apartment of an apparent heroin overdose, law enforcement sources said.

Hoffman was found with a syringe in his arm on the bathroom floor of his West Village apartment by a friend Sunday morning at about 11:30 a.m., and authorities think he had been dead several hours, sources told NBC 4 New York. Several empty bags were found throughout the apartment that were believed to have contained heroin.

A screenwriter friend, who was let into the apartment by Hoffman's assistant, came over to look for him after he was supposed to meet his children earlier in the day and did not show.

Hoffman, who was 46, won the Oscar for Best Actor in 2006 for his starring role in "Capote." He was nominated for Oscars three other times, including for 2012's "The Master," and he earned two Tony nominations for his work on Broadway.

He often played comic, slightly off-kilter roles in movies like "Along Came Polly," ''The Big Lebowski" and "Almost Famous." More recently, he was Plutarch Heavensbee in "The Hunger Games: Catching Fire" and was reprising that role in the two-part sequel, "The Hunger Games: Mockingjay," which is in the works. And in "Moneyball," he played Art Howe, the grumpy manager of the Oakland Athletics who resisted new thinking about baseball talent.

Just weeks ago, Showtime announced Hoffman would star in "Happyish," a new comedy series about a middle-aged man's pursuit of happiness.

Hoffman spoke candidly over the years about past struggles with drug addiction. After 23 years sober, he admitted in interviews last year to falling off the wagon and developing a heroin problem that led to a stint in rehab.

Hoffman's family released a statement on Sunday saying they were "devastated by the loss of our beloved Phil."

"This is a tragic and sudden loss and we ask that you respect our privacy during this time of grieving," the statement said. "Please keep Phil in your thoughts and prayers.”

Born in 1967 in Fairport, N.Y., Hoffman was interested in acting from an early age, mesmerized at 12 by a local production of Arthur Miller's "All My Sons." He studied theater as a teenager with the New York State Summer School of the Arts and the Circle in the Square Theatre. He then majored in drama at New York University's Tisch School of the Arts.

Trained in the theater, he was a character actor who could took on versatile roles that were variously large and small, loathsome and sympathetic.

On the stage, he performed in revivals of "True West," ''Long Day's Journey Into Night" and "The Seagull," a summer production that also featured Meryl Streep and Kevin Kline. In 2012, he took on one of the great roles in American theater, Willy Loman in "Death of a Salesman."

Hoffman leaves behind his partner of 15 years, Mimi O'Donnell, and their three children.